The storage industry is continually faced with customer demands for ever-greater storage capacity. Customers and end users desire that these new and improved data storage disk products be compatible and interchangeable with existing drive systems. In addition, the entertainment business, such as the movie industry and computer game manufacturers, has a need to confirm the authenticity of the content holding medium and to determine the proper mode of operation of a particular drive based on the disk that is being used. Disk drives for receiving media such as removable data storage disks must have some mechanism for detecting the insertion or presence of a data storage disk in the drive. For some disk drive systems, it is desired that the actuator that carries the recording heads of the drive across the surface of the data storage disk not be allowed to move and engage the disk unless the disk is compatible with that drive. This is important in order to avoid damage to the drive and head assembly that may result from an incompatible disk. Due to the removability feature of the disks with various drive types, an opening is provided in the disk drive to allow for the insertion and removal of the data storage disks. This feature allows for the possibility of foreign objects or incompatible disk being inserted into the drive, which could result in damage to the drive. Also, the spindle motor of the drive may be inadvertently activated by the detection of a foreign object, thereby generating particle debris in the drive.
Prior cartridge type products, such as floppy disks, have used switches triggered by differences in the cartridge to determine disk type. These mechanical switches are typically employed to detect the presence of a data storage disk having a cartridge within the drive. For example, a 21 MB floptical disk has different locations and quantity of depressions in the lower portion of its cartridge as compared to a 2 MB floppy for use with the same disk drive system. The switches activated by the arrangement of depressions enable the proper drive elements for that cartridge to operate properly.
Prior cartridge type products have also used a retro-reflective marker to determine disk type. "RETRO-REFLECTIVE MARKER FOR DATA STORAGE CARTRIDGE", U.S. Pat. No. 5,638,228, to Thomas, III, describes the reflection of a highly concentrated quasi circular lobe of light whose spread on reflection is captured by the aperture of a phototransistor in close proximity to a light emitting diode (LED). This excitor/detector pair is in the drive and a retro-reflective array is on the cartridge. The desired light lobe size is provided by the geometric size of the retro-reflector array elements relative to the spacing of the excitor and the detector in the drive. Due to this physical size matching and the fact that retro-reflectors are used, this marker on the cartridge is quite insensitive to cartridge tilt and distance from the excitor/detector pair in the drive. Another problem associated with the detection of LED light reflected from any reflective material is the occurrence of illuminance hot spots or structure in the LED output which often results in uneven illumination of the cartridge marker. Reflective cartridge markers can also become faded, scratched, or soiled. These factors combine to make the amplitude of the detected light signal highly variable. This patent is incorporated herein by reference.
Recently, in various industries such as the distribution industry, phosphors have been used in the control of goods by means of bar codes, and furthermore, bar codes are printed on various prepaid cards and passing cards, and these bar codes are read by optical reading apparatuses such as scanners to perform the desired actions. Moreover, various attempts have been made to apply forgery preventive means to credit cards and prepaid cards or to detect forged cards. For example, the marks, such as bar codes, are printed with an ink containing a phosphor by offset printing or by using an ink ribbon to form latent image marks. The latent image marks are irradiated with a semiconductor laser beam to excite the phosphor and the light emitted from the phosphor is received to read the bar code information by an optical reading apparatus. These techniques use the spectral content of the latent irradiance for identification.
"LATENT ILLUMINANCE DISCRIMINATION MARKER FOR DATA STORAGE CARTRIDGES", filed concurrently with this application, Thomas III, et al. U.S. patent application Ser. No. 09/161,007, describes a system for identifying and discriminating removable data storage cartridges and a data storage drive for receiving the cartridge. This system relates to the detection of the correct disk cartridge in the data storage drive by use of the decay time of a latent illuminance tag, preferably a phosphor tag disposed on the cartridge.
However, many data storage products do not have a carrier or cartridge for the disk, including optical data storage products such as ROM CD, R/W CD, and Write Once CD. This creates a problem of limited detection and validation options because the above described cartridge based detection and validation mechanisms are no longer feasible. Thus, traditional cartridge type detection systems are not suitable for current removable disks, such as CD type media, because these systems generally do not use a cartridge or carrier for the disk. Accordingly, there is a need to differentiate various types of disks that have no cartridge or carrier, preferably using components of current disk drives.
The product designer is thus faced with the problem of determining which type of disk and data storage media is currently in the drive and how to handle it physically. These issues include for example, setting disk spin rate, laser write power, determining disk type, servo implementation for media, and error correction code implementation. There is also a need to insure that some types of disks, such as movies and computer games, are authentic copies. With the coming to market of several types of high density removable data storage products such as writable CD, DVD products, high density flexible magnetic storage, rigid magnetic platter cartridges, photo-magnetic disks, phase change disks, and write-once optical disks with organic dye, as well as optical disks and magnetic tape products, double sided disks composed of two thin-type single sided disks stuck back to back, and multi-layer optical disks, the likelihood of unlicensed replication and sale of content on data storage disks is at an all time high.
Recently, several methods have been used to discriminate cartridgeless type disks. For example, one conventional disk drive system can play both a laser disk and a compact disk. This system first determines the size of a disk placed on the turntable (the two disks have different sizes), and then plays the disk using the appropriate method according to the size of the disk. However, for reading disks that have the same size, this mechanical method of disk discrimination is difficult.
The problem of disk distinction where the drive is capable of reading disks of the same size has been addressed by focusing on different recording densities of each disk, such as the compact disk and digital video disk. "DISK DISCRIMINATING METHOD AND APPARATUS", U.S. Pat. No. 5,745,460, Tateishi et al., describes a disk discriminating method and a disk discriminating apparatus in a disk drive, which distinguishes between disks of different recording systems based on the different recording densities of each disk. While a disk is rotated by a constant number of rotations, a recorded signal is read from the disk to acquire a read signal, one of the maximum period, minimum period, maximum inversion interval, minimum inversion interval and average frequency of the read signal is detected, and the type of the disk is determined in accordance with the detected value. However, this discrimination system is limited to applications where disk densities are readily distinguishable and require activation and engagement of the drive and head assembly.
Another method for optically discriminating types of disks having the same size is described in Japanese Patent Application Laid Open as a Provisional Publication No. 76061/87, which describes a reproduction unit using automatic discrimination for both the ordinary CD and the write-once CD having different reflectivities. A signal level obtained from an optical head is measured for determining a disk type when an object lens is approaching near focal point in a focus searching operation. However, currently available and proposed optical disks have a very high density in order to carry a huge amount of data, such as digital video data. Due to these very high density disks, this method is not adequate to reliably discriminate between different types of disks based only on their reflectivity.
"METHOD AND A SYSTEM OF OPTICAL DISK AUTO-DISCRIMINATING", U.S. Pat. No. 5,745,461, Kawasaki, et al., attempts to solve this problem by providing a method and system of automatic discrimination of types of optical disks according to differences in their recording density, number and material of their recording layer, and their disk thickness, i.e., either single sided or double sided. This method has difficulties in distinguishing disks having relatively similar densities, and requires numerous parameters be monitored and evaluated to correctly determine the type of disk in the drive.
The ability to discriminate between disk types after insertion into a data storage device but prior to engaging the read/write heads or other disk drive components is of significant value and utility. Principally this utility comes from the ability to detect the difference between various capacities or generations of data storage disks in a downward media compatible data storage drive. This discrimination capability allows for drive/media specific adjustments to be made, such as disk rotation rate, data channel rates, location of Z track for initial seeking, and mechanical adjustment in the drive like the active engagement of new crash stop locations. The ability of a disk drive to predetermine the type/generation of data storage disk inserted into it prior to enabling the spin-up and engagement of read/write elements also provides the drive system designer with new possibilities for cross-platform interchangeability.
Some means to authenticate the true licensed content holding disk is of significant value to prevent damage or destruction of drive systems and to protect a copyright holder's interest. A reliable device of automatic discrimination applicable for these various types of optical disks is desired. It is also desirable to use the existing drive components in a drive system for detecting and validating the data storage disk.
Although the art of detecting and discriminating between data storage disks is well developed, there remain some problems inherent in this technology, particularly when the disk is cartridgeless. Therefore, a need exists for a marker that produces reliable detection and discrimination between cartridgeless data storage disks.